Silicon Carbide: Manufacturing Processes and Material Properties B. C. Bigelow, UM Physics 3/24/05 3/24/05 Bruce C. Bigelow -- UM Physics

Silicon Carbide for SNAP Motivations: Silicon Carbide has extreme material properties Very high thermal conductivity Very low thermal expansion – close match to Si Very high specific stiffness (E/r) Fabrication processes have matured Process-tunable material properties Complex geometries, assemblies Substantial space heritage exists Space science applications Military applications Structures and reflecting optics 3/24/05 Bruce C. Bigelow -- UM Physics

Silicon Carbide for SNAP This talk: Brief history Manufacturing processes Commercial sources Material properties Spacecraft heritage Current applications Conclusions 3/24/05 Bruce C. Bigelow -- UM Physics

Silicon Carbide for SNAP History: Accidentally discovered by Edward G. Acheson (assistant to Thomas Edison) in 1890, while trying to synthesize diamond. First synthesis method - “Acheson Process” – SiC created intentionally by passing current through a mixture of clay and carbon “Natural” SiC found only in meteorites, in very small quantities 3/24/05 Bruce C. Bigelow -- UM Physics

Silicon Carbide for SNAP SiC Raw Material Production: Acheson Process – for producing powders Pyrolysis – for producing fibers Reactions of silicon and carbon – for producing whiskers 3/24/05 Bruce C. Bigelow -- UM Physics

SiC Production Processes Chemical Vapor Deposition (CVD); 99+% theoretical density, single phase Chemical Vapor Composite (CVC); CVD with particulate injection (Trex) Chemical Vapor Infiltration (CVI); graphite or carbon conversion / infiltration; graphite “greenbody”, may be reinforced with carbon or other fibers (C/SiC), multi-phase final material, porosity varies with process, also called Ceramic Matrix Composite (CMC) Sintering; trace amounts of impurities and second phase result from sintering additives, few percent porosity Slip Casting; similar to sintering, with liquid mold-filling additives Reaction Bonding; two phase mixture of SiC and Si, percentages and porosity vary with process Hot Isostatic Pressing (HIP); near-theoretical density, may have second phase or impurities from hot-pressing additives, can be very low porosity (inert gas compaction) Hot Pressing; mechanical pressure compaction with electric current heating 3/24/05 Bruce C. Bigelow -- UM Physics

Selected Sources for SiC BOOSTEC (Tarbes, France) Cercom (Vista, CA) Ceradyn (Costa Mesa, CA) Coorstek (Golden, CO) GE Power System Composites (Newark, DE) IBCOL (Munich, Germany) Kyocera Advanced Materials (Vancouver, WA) Poco Graphite (Decatur, TX) SSG Precision Optronics (Wilmington, MA) – no mat props. Trex Enterprises (Lihue, HI) Rohm & Haas (Woburn, MA) Saint Gobain / Carborundum (Niagara Falls, NY) 3/24/05 Bruce C. Bigelow -- UM Physics

SiC fabrication - IBCOL 3/24/05 Bruce C. Bigelow -- UM Physics

SiC fabrication - Boostec Picture of the Week SiC fabrication - Boostec 3/24/05 Bruce C. Bigelow -- UM Physics

R. Temp SiC Material Properties Manuf. Process E, GPa Fl. Str, Mpa Kic, MPa*m0.5 Density, kg/m^3 Poisson ratio CTE, ppm/C K, W/m*K Boostec sintered 420 450 3.5 >3100 0.16 4.0 180 Ceradyne CVD 440 375 3.1 3200 0.17 4.5 200 HP 634 4.3 4.8 115 430 400 120 Cercom CVI 460 570 4.4 130 Coorstek 462 468 3210 0.21 4.6 RB 4-5 3100 0.20 125 410 480 3150 150 GE Cesic C/SiC 197 2650 2.1 IBCOL 235 175 2.6 135 Kyocera 539 5.6 63 Poco 218 147 2.3 2530 1.2 170 Rohm-Haas 466 461 3.3 2.2 300 St.Gobain 240 0.14 Trex 380 3.4 205-250 3/24/05 Bruce C. Bigelow -- UM Physics

SiC Mat. Prop. Comparisons Manuf. Process E, GPa Fl. Str, Mpa Kic, Mpa-m-0.5 Density, kg/m^3 Poisson ratio CTE, ppm/C K, W/m*K Ceradyne CVD 440 375 3.1 3200 0.17 4.5 200 Coorstek 462 468 3.5 3210 0.21 4.6 115 Rohm-Haas 466 461 3.3 2.2 300 Trex 380 3.4 205-250 GE Cesic C/SiC 197 120 4.62 2650 2.1 125 IBCOL 235 175 2.6 135 AlN 330 290 3260 0.24 170 Alum 7075-T6 72 50 24 2790 0.33 23.4 160 TZM Arc cast 325 860 6-30 10160 0.32 4.9 Molybdenum Stress rel. 415 10220 5.35 138 304 St. Stl. 193 500 346 8030 0.29 16.2 16 3/24/05 Bruce C. Bigelow -- UM Physics

Bruce C. Bigelow -- UM Physics SiC Space Heritage Heritage missions: NASA EO-1 ALI – SiC mirrors ESA ROCSAT2 – SiC optical bench ESA ROSETTA – SiC optical bench 3/24/05 Bruce C. Bigelow -- UM Physics

Bruce C. Bigelow -- UM Physics SiC Space Heritage – EO1 3/24/05 Bruce C. Bigelow -- UM Physics

SiC Space Heritage – Rosetta Rosetta – SiC optics and optical bench 3/24/05 Bruce C. Bigelow -- UM Physics

SiC Space Heritage - ESA IBCOL EADS/ESA verification structure 3/24/05 Bruce C. Bigelow -- UM Physics

SiC Space Applications - Hershel 3.5m SiC primary mirror 3/24/05 Bruce C. Bigelow -- UM Physics

SiC Space Applications - Hershel Hershel SiC secondary mirror support structure 3/24/05 Bruce C. Bigelow -- UM Physics

ESA - GAIA GAIA optical layout – 2 fields simultaneously 3/24/05 Bruce C. Bigelow -- UM Physics

Bruce C. Bigelow -- UM Physics ESA - GAIA GAIA focal plane mosaic – 10 x 18 = 180 CCDs 4500 x 1966 px/CCD, 1.5 Gpx 3/24/05 Bruce C. Bigelow -- UM Physics

SiC Space Applications - GAIA Picture of the Week SiC Space Applications - GAIA GAIA SiC primary mirror demonstrator - 1.4m x 0.5m 3/24/05 Bruce C. Bigelow -- UM Physics

SiC Space Applications - GAIA Picture of the Week SiC Space Applications - GAIA GAIA SiC stability verification optical bench 3/24/05 Bruce C. Bigelow -- UM Physics

SiC Space Applications - GAIA Picture of the Week SiC Space Applications - GAIA GAIA focal plane demonstrator model (Boostec): 770mm by 580mm by 36mm, with a mass of about 8kg. 3/24/05 Bruce C. Bigelow -- UM Physics

SiC Space Applications - GAIA Picture of the Week SiC Space Applications - GAIA GAIA focal plane - sintered SiC – detector mounting detail 3/24/05 Bruce C. Bigelow -- UM Physics

Silicon Carbide for SNAP Conclusions: There are many commercial sources for SiC SiC material production and fabrication methods are well developed SiC and C/SiC demonstrate extremely high performance material properties Space heritage for SiC has been established NASA and ESA are using of SiC in current programs SiC is a real option for SNAP, both for optics and structures 3/24/05 Bruce C. Bigelow -- UM Physics